Temperature responsive control



Nov. 29, 1949 F. c. BROCKMAN TEMPERATURE RESPONSIVE CONTROL Filed Aug. 15, 1946 Fig.2.

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Hi 3 Att orn ey- Patented Nov. 29, 1949 TEMPERATURE RESPONSIVE CONTROL Francis 0. Brockman, Glen Ridge, N. J assignor to General Electric Company, a corporation of New York Application August 13, 1946, Serial No. 690,297

Claims. 1

The invention relates to temperature responsive control and particularly to blmetal operated .push switches suitable for warm air furnace fan control or other similar temperature responsive control service. i

In warm air furnace fan control service, it is desirable that the push switch bimetal operating element be spaced apart inside an air duct so as to be fully exposed to warm air flow through the duct or the like in order to obtain a quick and accurate response while the push switch itself is mounted so as to be readily accessible outside the duct for wiring and servicing. Likewise it may be desirable to have accessible the warm air temperature setting control as well as an improved manual control for running the fan for cooling purposes independently of the warm air furnace temperature.

Thus one object of the present invention is to provide an improved spaced apart temperature responsive push switch mounting and operating arrangement wherein the cooperating relations indicated above of the temperature responsive operating element, the push switch, and the temperature adjustment control are obtained in an improved way.

Another object is to construct the temperature of responsive push switch so that the switch mounting plate will form a closure for an opening into a warm air duct or the like with the temperature responsive bimetal operating element and the push switch spaced apart on opposite sides of the mounting plate and with a reciprocating push rod extending through the plate between the push switch and the operating element and also a rotary control member extending through the plate for calibrating the operating element.

Another object is to provide an improved form of temperature setting or adjustment control utilizing a bendable mounting member extending from the mounting plate and secured to one end of the bimetal operating element and provided with an adjusting screw rotatably anchored in the mounting plate.

Another object is to combine with the improved temperature adjustment control mechanism, an improved form of manual contro1 arranged to bend or flex the bimetal to enforce operation of view, partly in section, of the improved combined manual and temperature responsive push switch construction of the present invention wherein the mounting plate of the switch serves to close an opening into an air duct or the like; and Fig. 2 is a front view indicating the arrangement of the summer and winter manual adjustment mechanism and the push switch mechanism on the switch mounting plate and indicating by dotted lines the temperature responsive bimetal operating element on the opposite side of the plate; and Fig. 3 schematically shows the improved switch applied to control the operation of an electric motor driven circulating fan of a warm air furnace.

As shown in Fig. 1 the normally open push switch ill may be of the well known enclosed snap-action type now in common use, and is provided with the wiring terminals 1 I and the switch operating push button l2. Switch it is mounted within the partial enclosing channel I3 by means of the mounting screws i4 and is provided with the push rod I5 extending through the opening l6 formed in one side of the channel l3 and having an enlarged cup I! for receiving the push button l2 therein to operate switch in. The one side of the switch mounting channel [3 is extended so as to form a plate 20 that will serve to close the opening 2! formed in the side wall 22 of an air duct or the like with the edges of the plate 20 overlapping the sides of the opening 2| as indicated by the dotted lines in Fig. 2. The push switch mounting plate 20 is secured to the wall 22 by means of the mounting screws 23.

The temperature responsive bimetal operating element 25 is U-shaped as indicated in Fig. 1 with one leg of the U 26 extended beyond the other so as to operatively engage with the end of the push rod i5 for operating switch ID. A headed pin 21 loosely extends through a suitable hole '24 formed in the extended leg 26 of bimetal 25 and is anchored in the end of push rod l5 so as to provide a lost motion connection between the rod and the bimetal. A bendable mounting member 28 for the operating element 25 is fixedly mounted at one end 29 upon the plate 20, preferably being welded thereto. The short leg 38 of bimetal element 25 is secured to the bendable mounting member 28 by means of the bolt 3!.

the switch in the summer independently of tem- In this way the thermal bimetal responsive eleperature so as to run the fan for cooling purposes.

Other objects and advantages of the invention will appear in the following-description of the ment 25 is adjustably mounted and spaced apart from the plate 20 so as to be exposed fully to the warm air fiow inside of the duct 32 and thereby become more quickly and accuratel reaccompanying drawing in which Fig. 1 is a. side 56 sponsive to variations in the temperature of the 3 air. When the switch is to be used in warm air furnace fan control service the bimetal 25 is formed so that the extended leg 26 moves towards the plate 20 in response to heating of the bimetal and away from plate 20 inresponse to cooling of the bimetal.

In order to control the temperature to which bimetal 25 responds to operate the push switch ID, the headed adjusting screw or bolt 33 is provided. As shown in Fig. 1 the headed end 33a of adjusting screw or bolt 33 is rotatably supported in plate 20, being maintained in operating position by means of the thrust ring 34-, with the threaded end 33b in screw threaded engagement with the bendable mounting member 28. Thus by rotating the adjusting screw or bolt 33, the mounting member 28 may be bent either towards or away from plate 20 so as to correspondingly vary the spaced apart position of bimetal element 25 and thus correspondingly vary the temperature at which bimetal element 25 operates switch H1. Any suitable means may be provided for maintaining the temperature adjustment control member 33 in its adjusted position. However, when the switch is to be used in warm air furnaces fan control service where a relatively fixed temperature is involved, then the headed end 33a may be secured by soldering to plate 20 after the proper adjustment for the desired temperature has been made.

Since in the summer it may be desired to close switch in manually irrespective of temperature, an improved form of manual switch operating mechanism is provided. As shown in Fig. 1, the temperature adjusting screw or bolt 33 is provided with an internal threaded opening 35 and with the rotatable shaft 36 in threaded engagement therewith. Preferably the threads are of steep pitch so that a relatively large axial movement of the shaft 36 is obtained upon rotation thereof. For this purpose the shaft 36 is provided with a manual operating lever 3'1 clamped thereto by means of the screw 38. The locknuts 39 are adjustable on the threaded end of the shaft 36 so as to engage with and bend the extended leg 26 of bimetal 25 to operate switch l when shaft 36 is rotated in one direction.

However with lever 31 in the winter operating position as indicated in Fig. 2, the stop-nuts 39 are moved sufiiciently far away from plate 26 to enable the bimetal element 25 to move towards and away from plate 20 entirely in response to temperature variations so as to respectively close and open the normally open switch ill. The lost motion provided by pin 21 enables such temperature responsive operation of the switch to be obtained without binding of any of the parts. Furthermore, pin 21 and the sliding bearing of the rod IS with the opening l6 serves to maintain the push rod I in proper alignment with the push button l2 even though the bimetal 25 should be subjected to wide temperature variations.

Upon rotation of the manual operating'lever 31 from the winter position in which it is shown in Fig. 2 to the summer position, shaft 36 is rotated to carry the stop-nuts 39 into engagement with the extended leg 26 of bimetal 25 and thereby bend the bimetal irrespective of the temperature so as to take up the lost motion and operate push rod [5 to push the button I! and thereby close switch l0. Thus when the improved combined manual and temperature responsive switch is applied to warm air furnace 4 fan control service as indicated in Fig. 3, automatic temperature responsive operation of the fan will be obtained in the winter and manually controlled enforced operation of the fan obtained in the summer.

As indicated schematically in Fig. 3, the switch I0 controls the operation of the electric motor 40' that drives by means of belt ll the air circulating fan 42 of the warm air furnace 43 having th heat exchanger 44 for heating the air. The switch mounting plate 20 serves to close an opening into the warm air ducts of furnace 43 with the temperature responsive bimetal operating element quickly responsive to variations of the temperature of the air inside the duct. However, the switch I!) as well as the manual operating lever 31 are readily accessible outside the duct and furthermore are not subject to direct heating by the furnace heat exchange surface M.

What I claim as new and desire to secure by Letters Patent of the United States is:

.1. In combination a switch having a mounting plate extended off one side thereof to form a closure for a wall opening in an air duct or the like with the said switch mounted on the outside of the duct and an operating push rod extended through said plate, a temperature responsive bimetal strip spaced apart from the inner side of said plate and having one end operatively connected to reciprocate said rod and thereby operate said switch, and an adjustable mounting member secured to and extended between said strip and said plate and provided with an adjustment control member extended through said plate for varying the position of said strip and thereby controlling the temperature at which said strip responds to operate said switch.

2. In combination a switch'having a mounting plate extended to form a closure for a wall opening in an air duct or similar member with the said switch mounted on the outside of the opening and a push rod extended through said plate, a U-shaped temperature responsive bimetal element having one end movable towards and away from said plate and operatively connected to reciprocate said rod and thereby operate said switch, a bendable mounting member secured to the other end of said element and fixed to the inside of said plate and provided with an adjusting screw extended through and rotatably anchored in said plate for bending said member to vary the position of said element and thereby control the temperature at which said element responds to operate said switch.

3. In combination a switch having a mounting channel and a push rod extended through one side wall thereof with said wall extended to form a closure for an opening into an air duct, an air temperature responsive U-shaped bimetal element having a free end movable towards and away from said channel and operatively connected to reciprocate said rod, a bendable mounting member secured to the other end of said element and fixed to said extended side wall, and an adjusting screw having a headed end rotatably anchored in said side wall and a threaded end in screw threaded engagement with said bendable member for bending said member to vary the position of said element and thereby control .the temperature to which said element responds to operate said switch.

4. In combination an enclosed snap-action push switch having a mounting channel and a push 76 rod extended through one side wall thereof with said side wall extended to form a closure for an opening into an air duct, a temperature responsive U-shaped bimetal element having one leg extended for operative connection to reciprocate said rod, 9. bendable mounting member secured to the other leg of said element and fixed to said plate, and a hollow adjusting screw hav ing a headed end rotatabiy anchored in said plate and a threaded end in screw threaded engagement with said bendable member for bending said member to vary the position of said element and thereby control the temperature to which said element responds to operate said switch, said adjusting screw being provided with an internal thread, and manual switch operating means including a shaft extending through said adjusting screw in internal threaded engagement therewith and provided with stop means for engaging and bending said extended leg of said element independently of temperature to operate said switch.

5. A summer-winter fan control having in combination a plate for closing an opening in an air duct, fan control means including a switch mounted on the outside of said plate, a temperature responsive movable element having means for adjustably mounting said element on the inside of said plate, said element having a connection extending through said plate for operating said switch, and separate means for moving said element to operate said switch independently of temperature, said means including a manually operable member outside said plate, a hollow ad- Justment screw rotatably anchored in said plate and provided with an internal thread, a shaft extending through said adjusting screw in threaded engagement therewith and provided with stop means for engaging and drawing said element towards the said plate.

FRANCIS C. BROCKMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,942,697 Henning Jan. 9, 1934 1,956,608 Bailey May 1, 1934 1,961,649 Stewart June 5, 1934 2,164,312 Drake July 4, 1939 2,192,633 Beam Mar. 5, 1940 2,269,863 Shaw Jan. 13, 1942 2,372,491 Hausler Mar. 2'7, i945 

